Radial cutter bit with cutting insert having edge preparation

ABSTRACT

A radial cutter bit includes a non-rotatable shank portion, a head portion including a tip region distal from the non-rotatable shank portion, and a cutting insert mounted at the tip region of the head portion. The cutting insert includes a body having a leading face, an opposing trailing face, a first side and a second side. The leading face has a central face portion, a first side face portion extending toward the first side of the body and a second face portion extending toward the second side of the body. The cutting insert further includes a top surface having a relief surface, a T-land surface extending between at least a portion of the leading face and the relief surface of the top surface and a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.

BACKGROUND OF THE INVENTION

The invention pertains generally to an excavating tool such as, for example, a cutter bit useful for cutting through various earth strata and other materials. More specifically, the invention pertains to a radial cutter bit with a cutting insert having edge preparation.

Various types of cutting assemblies having cutter bits are used for mining, construction and related operations wherein, typically, the cutter bits include a shank for insertion into a tool holder and a forward working portion on the shank for engagement with earth strata, e.g., coal, or mineral formation or other natural materials or the like. An individual insert formed of a hard, wear resistant material is provided on the forward working portion to cut into the earth strata and to enhance the life of the cutter bit as it removes the material.

An example of a cutting assembly having cutter bits that are used for mining and construction operations is a radial cutter tool. These types of cutting tools usually include a plurality of cutter bits mounted on a rotatable disc, rake, chain, barrel or drum, wherein each of the cutter bits include a substantially-flat cutting insert made of a hard material. These substantially-flat cutting inserts are affixed to the forward working end of the cutter bits. However, it has been determined that due to the shape and configuration of the substantially-flat cutter inserts, the cutter inserts do not wear uniformly. This non-uniform wear decreases the overall useful life of the cutting inserts. More particularly, the cutting edge of the substantially-flat cutter inserts have a tendency to chip or break during use due to the shape of the cutting edge.

Accordingly, it would be desirable to provide improved cutting tools that overcome limitations and disadvantages of known such tools. In addition, it would be desirable to provide improved cutter bits that overcome limitations and disadvantages of known cutter bits and that provide for improved wear and efficiency during operation. Furthermore, it would be desirable to provide improved cutting inserts for cutter bits that overcome limitations and disadvantages of known cutting inserts and that provide for improved wear and efficiency during operation.

SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, a radial cutter bit for engaging an earth strata material includes a non-rotatable shank portion, a head portion integrally formed with the non-rotatable shank portion and including a tip region distal from the non-rotatable shank portion, and a cutting insert mounted at the tip region of the head portion. The cutting insert includes a body having a leading face, an opposing trailing face, a first side and a second side. The leading face has a central face portion, a first side face portion extending toward the first side of the body and a second face portion extending toward the second side of the body. The cutting insert further includes a top surface having a relief surface, a T-land surface extending between at least a portion of the leading face and the relief surface of the top surface and a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.

In accordance with another aspect of the invention, a cutting insert for use in connection with a cutter bit for engaging an earth strata material includes a body having a leading face, an opposing trailing face, a first side and a second side. The leading face has a central face portion, a first side face portion extending toward the first side of the body and a second face portion extending toward the second side of the body. The cutting insert further includes a top surface having a relief surface, a T-land surface extending between at least a portion of the leading face and the relief surface of the top surface and a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.

These and other aspects of the present invention will be more fully understood following a review of this specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a cutter bit, e.g. a radial cutter bit, in accordance with an aspect of the invention.

FIG. 2 is a front view of the cutter bit shown in FIG. 1, in accordance with an aspect of the invention.

FIG. 3 is a front view of a cutting insert for use with the cutter bit shown in FIGS. 1 and 2, in accordance with an aspect of the invention.

FIG. 4 is a top view of the cutting insert shown in FIG. 3, in accordance with an aspect of the invention.

FIG. 4A is a sectional view taken along line 4A-4A of FIG. 4, in accordance with another aspect of the invention.

FIG. 4B is a sectional view taken along line 4B-4B of FIG. 4, in accordance with another aspect of the invention.

FIG. 4C is a sectional view taken along line 4C-4C of FIG. 4, in accordance with another aspect of the invention.

DETAILED DESCRIPTION

The following description is for purposes of illustrating various aspects of the invention only and not for purposes of limiting the scope of the invention.

Referring to FIGS. 1-4C, there is illustrated a cutter bit in the form of, for example, a radial cutter bit generally designated as 10, and a cutting insert generally designated as 22 for use therewith. The radial cutter bit 10 includes a shank portion 12 that is non-rotatable, i.e. the shank portion 12 does not rotate during operation once the radial cutter bit 10 is assembled by inserting the shank portion 12 of the radial cutting tool 10 into a tool holder base (not shown). In one aspect, the shank portion 12 has a generally non-circular cross-section, e.g. a generally rectangular cross-section.

The radial cutter bit 10 includes a forward working end that includes a head portion 14 integrally formed with the shank portion 12 and having a tip region 16 distal from the shank portion 12. The cutting insert 22 is mounted at the tip region 16 of the head portion 14. The cutting insert 22 is typically mounted or affixed to the head portion 14 by, for example, attaching mechanically or otherwise, via brazing, gluing, or press fitting using conventional compositions and techniques known to those skilled in the art.

The cutting insert 22 is made from, for example, a cemented tungsten carbide that is a mixture of cobalt and tungsten carbide. Other super hard, wear resistant materials such as polycrystalline diamond, ceramics, or cermet may be used as a supplement and/or substitute. For example chromium carbide-coated metals and other cermets where titanium carbide or vanadium carbide is added to tungsten carbide may be candidates for inserts materials in accordance to aspects of the invention. Alternate ceramics for such applications include aluminum-based, silicon based, zirconium-based and glass varieties. Still other insert materials alternatives include cubic refractory, transition metal carbides or any other known or subsequently developed material(s) harder than the base material. Also coatings of the inserts such as PVD or CVD coatings can be used.

In one aspect, the cutting insert 22 is made, for example, with a powder metallurgy process using a press comprising of a die and top and bottom ram/punch to press the complete shape. Parts can be pressed to finished shape or modified with a wet/dry blast, or diamond ground other material shaping processes such as but not limited to EDM (electrical discharge machining), EDG (electrical discharge grinding), green machining, laser ablation into final shapes. Advantageously, the invention provides for moving the critical cutting edge of the insert from the intersection of the die case and ram during manufacturing. In accordance with an aspect of the invention, the critical cutting edge is now formed entirely in the ram/punch. This eliminates the flash from forming on the cutting edge. Flash is undesirable because, for example, it is a stress concentrator. It will be appreciated that these and other aspects of the invention as set forth herein contribute to the desired edge, i.e. cutting edge, preparation for the cutting insert.

Cutting insert 22 has a cutting insert body, generally designated as 24, that has a top surface 26, a bottom surface 28, a first side portion 34 and a second side portion 36. The cutting insert body 24 also includes a leading face 40 and an opposite rearward or trailing face 42.

The leading face 40 includes a central face portion 40 a, a first side face portion 40 b extending toward the first side portion 34 of the body 24 and a second side face portion 40 c extending toward the second side portion 36 of the body 24. In one aspect, the central face portion 40 a is contiguous and non-coplanar with the first side face portion 40 b. In another aspect, the central face portion 40 a is contiguous and non-coplanar with the second side face portion 40 c.

The top surface 26 of the cutting insert 22 includes a relief surface 44. In one aspect, the relief surface 44 extends toward the rearward or trailing face 42 of the cutting insert 22. In another aspect, the relief surface 44 extends to the rearward or trailing face 42. In another aspect, the relief surface is generally curved or arcuate.

In accordance with another aspect of the invention, the cutting insert 22 includes edge preparation such as a T-land surface, generally designated as 48, extending generally between at least a portion of the leading face 40 and the relief surface 44 of the top surface 26. In one aspect, the T-land surface 48 includes a central T-land surface 48 a extending between the central face portion 40 a of the leading face 40 and the relief surface 44 of the top surface 26, a first side T-land surface 48 b extending between the first side face portion 40 b of the leading face 40 and the relief surface 44 of the top surface 26 and a second side T-land surface 48 c extending between the second side face portion 40 c of the leading face 40 and the relief surface 44 of the top surface 26. In one aspect, the central T-land surface 48 a, the first side T-land surface 48 b and the second side T-land surface 48 c are contiguous with each other to provide for a continuous T-land surface 48. In one aspect, the central T-land surface 48 a is contiguous with the central face portion 40 a, the first side T-land surface 48 b is contiguous with the first side face portion 40 b and the second side T-land surface 48 c is contiguous with the second side face portion 40 c. In another aspect, the central T-land surface 48 a is contiguous with the relief surface 44, the first side T-land surface 48 b is contiguous with the relief surface 44 and the second side T-land surface 48 c is contiguous with the relief surface 44. It will be appreciated that the T-land surface(s) 48 may be planar surfaces or other than a planar surface, such as, for example it may include a rounded or curved, i.e. non-planar, T-land surface.

The cutting insert 22 further includes a cutting edge 50 formed at the intersection of the T-land surface 48 and the relief surface 44 of the top surface 26. In one aspect, the cutting edge 50 includes a central cutting edge 50 a formed at the intersection of the central T-land surface 48 a and the relief surface 44 of the top surface 26, a first side cutting edge 50 b formed at the intersection of the first side T-land surface 48 b and the relief surface 44 of the top surface 26 and a second side cutting edge 50 c formed at the intersection of the second side T-land surface 48 c and the relief surface 44 of the top surface 26. In another aspect, the central cutting edge 50 a, the first side cutting edge 50 b and the second side cutting edge 50 c are contiguous with each other to provide for a continuous cutting edge 50. In another aspect, the central cutting edge 50 a, the first side cutting edge 50 b and the second side cutting edge 50 c may be rounded or curved.

The configuration of having the central cutting edge 50 a formed at the intersection of the central T-land surface 48 a and the relief surface 44 provides for the cutting edge 50 a to have a negative axial rake angle Ra (see, for example, FIG. 4A). In one aspect, the negative axial rake angle Ra is in the range of about 10 degrees to about 60 degrees. In one specific example, the rake angle Ra shown in FIG. 4A is about negative 35 degrees.

The central T-land surface 48 a is positioned relative to the relief surface 44 at an angle Xa (see, for example, FIG. 4A). The angle Xa may be referred to as a relief angle relative to or in relation to cutting edge 50 a. In one aspect, the T-land surface 48 a is positioned relative to the relief surface 44 at an angle Xa that is greater than 90 degrees. In one specific example, the angle Xa shown in FIG. 4A is about 110 degrees.

In another aspect, the central T-land surface 48 a may have a width Wa (see, for example, FIG. 4A) in the range of about 0.002 inches to about 0.090 inches. In one specific example, the width Wa is about 0.010 inches.

The configuration of having the first side cutting edge 50 b formed at the intersection of the first side T-land surface 48 b and the relief surface 44 provides for the cutting edge 50 b to have a negative axial rake angle Rb (see, for example, FIG. 4B). In one aspect, the negative axial rake angle Rb is in the range of about 10 degrees to about 60 degrees. In one specific example, the rake angle Rb shown in FIG. 4B is about negative 50 degrees.

The first side T-land surface 48 b is positioned relative to the relief surface 44 at an angle Xb (see, for example, FIG. 4B). The angle Xb may be referred to as a relief angle relative to or in relation to cutting edge 50 b. In one aspect, the first side T-land surface 48 b is positioned relative to the relief surface 44 at an angle Xb that is greater than 90 degrees. In one specific example, the angle Xb shown in FIG. 4B is about 125 degrees.

In another aspect, the first side T-land surface 48 b may have a width Wb (see, for example, FIG. 4B) in the range of about 0.002 inches to about 0.090 inches. In one specific example, the width Wb is about 0.015 inches.

The configuration of having the second side cutting edge 50 c formed at the intersection of the second side T-land surface 48 c and the relief surface 44 provides for the cutting edge 50 c to have a negative axial rake angle Rc (see, for example, FIG. 4C). In one aspect, the negative axial rake angle Rc is in the range of about 10 degrees to about 60 degrees. In one specific example, the rake angle Rc shown in FIG. 4C is about negative 50 degrees.

The second side T-land surface 48 c is positioned relative to the relief surface 44 at an angle Xc (see, for example, FIG. 4C). The angle Xc may be referred to as a relief angle relative to or in relation to cutting edge 50 c. In one aspect, the second side T-land surface 48 c is positioned relative to the relief surface 44 at an angle Xc that is greater than 90 degrees. In one specific example, the angle Xc shown in FIG. 4C is about 125 degrees.

In another aspect, the second side T-land surface 48 c may have a width Wc (see, for example, FIG. 4C) in the range of about 0.002 inches to about 0.090 inches. In one specific example, the width Wc is about 0.015 inches.

It will be appreciated that the configuration of the T-land(s) 48, cutting edge(s) 50, negative axial rake angle(s) R and/or the relief angle(s) X individually and/or in combination advantageously avoid a sharp transition for the cutting edge(s) 50 so as to reduce or minimize the possibility of the cutting edge 50(s) breaking or chipping during operation of the cutter bit 10. In addition, the T-land(s) 48 is configured so as to redirect the cutting forces along the cutting edge(s) 50 to reduce the shear stress along the cutting edge(s) 50.

Whereas particular aspects of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims. 

What is claimed is:
 1. A radial cutter bit for engaging an earth strata material, the radial cutter bit comprising: a non-rotatable shank portion; a head portion integrally formed with the non-rotatable shank portion and including a tip region distal from the non-rotatable shank portion; and a cutting insert mounted at the tip region of the head portion, wherein the cutting insert comprises: a body having a leading face, an opposing trailing face, a first side and a second side; the leading face having a central face portion, a first side face portion extending toward the first side of the body and a second face portion extending toward the second side of the body; a top surface having a relief surface; a T-land surface extending between at least a portion of the leading face and the relief surface of the top surface; and a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.
 2. The radial cutter bit of claim 1, wherein the T-land surface includes a central T-land surface extending between the central face portion of the leading face and the relief surface of the top surface.
 3. The radial cutter bit of claim 2, wherein the cutting edge includes a central cutting edge formed at the intersection of the central T-land surface and the relief surface of the top surface.
 4. The radial cutter bit of claim 3, wherein the central cutting edge has a negative axial rake angle.
 5. The radial cutter bit of claim 1, wherein the T-land surface includes a first side T-land surface extending between the first side face portion of the leading face and the relief surface of the top surface.
 6. The radial cutter bit of claim 5, wherein the cutting edge includes a first side cutting edge formed at the intersection of the first side T-land surface and the relief surface of the top surface.
 7. The radial cutter bit of claim 6, wherein the first side cutting edge has a negative axial rake angle.
 8. The radial cutter bit of claim 1, wherein the T-land surface includes a second side T-land surface extending between the second side face portion of the leading face and the relief surface of the top surface.
 9. The radial cutter bit of claim 8, wherein the cutting edge includes a second side cutting edge formed at the intersection of the second side T-land surface and the relief surface of the top surface.
 10. The radial cutter bit of claim 9, wherein the second side cutting edge has a negative axial rake angle.
 11. A cutting insert for use in connection with a cutter bit for engaging an earth strata material, the cutting insert comprising: a body having a leading face, an opposing trailing face, a first side and a second side; the leading face having a central face portion, a first side face portion extending toward the first side of the body and a second face portion extending toward the second side of the body; a top surface having a relief surface; a T-land surface extending between at least a portion of the leading face and the relief surface of the top surface; and a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.
 12. The cutting insert of claim 11, wherein the T-land surface includes a central T-land surface extending between the central face portion of the leading face and the relief surface, the cutting edge includes a central cutting edge formed at the intersection of the central T-land surface and the relief surface, and the central cutting edge has a negative axial rake angle.
 13. The cutting insert of claim 12, wherein the T-land surface includes a first side T-land surface extending between the first side face portion of the leading face and the relief surface, the cutting edge includes a first side cutting edge formed at the intersection of the first side T-land surface and the relief surface, and the first side cutting edge has a negative axial rake angle.
 14. The cutting insert of claim 13, wherein the T-land surface includes a second side T-land surface extending between the second side face portion of the leading face and the relief surface, the cutting edge includes a second side cutting edge formed at the intersection of the second side T-land surface and the relief surface, and the second side cutting edge has a negative axial rake angle.
 15. The cutting insert of claim 12, wherein the negative axial rake angle of the central cutting edge is in the range of about 10 degrees to about 60 degrees.
 16. The cutting insert of claim 13, wherein the negative axial rake angle of the first side cutting edge is in the range of about 10 degrees to about 60 degrees.
 17. The cutting insert of claim 14, wherein the negative axial rake angle of the second side cutting edge is in the range of about 10 degrees to about 60 degrees. 